Detachable lamp assembly for illuminating instruments



Nov. 27, 1951 W,

DETACHABLE LAMP ASSEMBLY FOR ILLUMINATING INSTRUMENTS Patented Nov. 27, 1951 DETACHABLE LAMP ASSEIVIBLY FOR ILLUMINATING INSTRUMENTS Weldon C. Emery, Des Moines, Iowa, assignor to Burlington Instrument Company, Burlington, Iowa, a corporation of Iowa Application March 30, 1948, Serial No. 17,931

1 Claim.

This invention relates to illuminated instruments and the like. More particularly, the invention relates to instrument casings and means for illuminating them. In some of its more specific aspects, the present invention pertains to novel means for assembling an illuminated instrument and supporting means for the illuminating elements of instruments and the like.

Instruments such as meters, gauges or indicaters empioyed in industrial establishments often require some form of auxiliary illumination inasmuch as the design or location of the instrument may be such that the face cannot be clearly seen nor can the indications thereon be easily observed with only the ordinary illumination available in the vicinity of the instrument. Therefore, many diierent illuminating means have been designed to provide auxiliary illumination for the face of said instruments by installing small electrically operated lamps either at the outside. of the instrument casing or frequently in the interior of the casing. Principally, it has been found to be more desirable to locate the lamps within the instrument casing, whereby the lamps are protected from damage and, at the same time, so that the glare thereof is shielded by the casing within which they are disposed.

It. has been difficult to provide satisfactory illuminating means and lamp supporting assemblies which are readily accessible for the purpose of replacing burned-out lamps, yet which are simple enough in construction and assembly that they may be quickly and easily replaced. This is particularly true of instruments having a semi-flush mounting on a wall or panel. As, will appear in detail hereinafter, the present invention provides a structure which has overcome the objectionable features of illuminated instruments known heretofore.

One of the objects of the present invention, therefore, is to provide illuminated instruments and the like having simple, readily accessible and easily replaceable illuminating means.

It is a further object of the invention to provide a new and novel support for the illuminating means whereby it may be placed within or removed from an instrument casing without interfering with the mechanisms Operating therein.

It is a further object to provide an assembly which may be installed and replaced without necessity for making or disconnecting cumbersome wire connections.

Other objects will be apparent from the following description and in the accompanying' drawings, wherein:

Figure 1 is a front elevation, partly in section. showing an instrument embodying the present invention;

Figure 2 is a side elevation of the instrument shown in Figure l;

Figure 3 is a bottom view of the instrument shown in Figure l;

Figure 4 is a front view of one form of the support for the illuminating means of the present invention as the assembly appears when removed, as a unit, from the instrument shown in Figures l to 3, inclusive;

Figure 5 is a plan view of the assembly shown in Figure 4; and

Figure 6 is a sectional elevation of one of the illuminating element sockets and supporting means of the present invention, taken through line I--G of Figure 5.

In the embodiment of the present invention as illustrated in Figures l to 3, inclusive, a hollow instrument casing Il made of a suitable dielectric material is provided with a rectangular cover plate I2 which includes a sight window I3 provided with a transparent closure such as glass plate I4. Casing Il also includes a semi-flush instrument case l5 having a flange portion i6 which is substantially iiush with the rear wall of casing Il, the case serving to support a suitable electric testing mechanism I'I, indicator needle I8 actuated by said testing mechanism and a scale plate I9 which is calibrated for reading the measurements taken by the instrument. Case I5 also carries electrical input terminals 20 and 2li through which the electrical energy or other impulse to be measured is conducted to the measuring instrument. The case I5 and its associated parts are held in assembled relationship with respect to rectangular cover plate l2 by means of screws in such manner that the rear face of the instrument may be mounted iiush with a wall panel or the like, thus providing the so-called semi-flush mounting.

The instrument as a whole is so designed that it may be easily attached to a wall or panel by means of threaded mounting studs 2l.

In apparatus of the type illustrated in the drawings it is usually desirable to provide suitable means for illuminating the calibrated scale plate l 9 upon which the measurement of electrical energy passing through the instrument may be registered. The instrument of the present invention is so designed as to permit easy withdrawal and replacement of suitable illuminating lamps without the necessity for connecting or disconnecting wires or the like and yet without disturbinor the indicating mechanism in any way.

It will be noted that the respective elements of the instrument are arranged in such manner that a number of the elements to the right f the-center of the instrument are interchangeabley with f and correspond to like elements to the left of the center of the instrument. This bilateral symmetry of the instrument facilitates maintenance and repair.

For this purpose a lamp mounting strip 22 which serves a a bottom closure plate and is made of a suitable dielectric material is provided with a terminal lug 23 offmetallic or other electrical conducting material inlaid in the uppermost'iace of the lamp mounting strip and a pair oi internally threaded lamp supporting sockets 24 and 24' which extend into the interior of casing H through-apertures 25 Vand 25', respectively, in the vbottom wall thereof. The lamp mounting strip 22 is tted snugly against the bottom wall of'casing l'l and is held in place by a single screw 26 seated in a countersunk bore in closure plate 22 in the manner shown in Figures l and 2 of the drawings. V

Incandescent lamps 21 and 21 are mounted in sockets 24 and 24', respectively, and are illuminated by means of an electrical circuit described in detail hereinafter.

For the purpose of supplying an electrical current of the proper voltage to illuminate lamps 21 and 21', lead wire 28 is connected at one end to a suitable battery or other electrical source (not shown) and at the opposite en'd is connected to contact clip assembly 29 as shown in Figures 2 and 3 of the drawings. v

Contact clip assembly '29 is made up of a threaded bolt 3! which extends rearwardly of the casing from the interior thereof through a bolt openingr in contact clip 32, spacer sleeve 33 and bolt hole 34 in the rear wall of case l5. The assembly is retained in place by a lock washer 35 which is urged against the inside of the'housing by means. of nut 36 threaded on the free end of bolt 3|.

lOn the left side of the center of the instrument, there is a corresponding contact clip assembly 29 including threaded bolt 3|', contact clip 32', spacer sleeve 33' and nut 3B' as shown in Figures l and 3 of the drawings.

When the A lamp supporting assembly is properly positioned in the bottom of the casing, it lwill be observedY that the outer wall of lamp socket 24 is in contact with contact clip 32 in such manner that electrical current may pass between the contacta-rm and the lamp socket.

A detailed showing of the lamp socket assembly is seen in Figures 4, 5 and 6 of the drawings. rlhe lamp socket 24, as shown in Figure 6, is supported by lamp mounting strip 22 in such manner that it is insulated from terminal lug 23. It will be understood that both lamp supporting sockets 24 and 24 `are mounted in this fashion, otherwise a short circuit would result. l'

A hollow rivet 43 of metallic or other electrical conducting material having a iiange 44 imbedded in the outer face of lamp supporting strip 22 passes through and in contact with terminal lug 23, insulating wash-ers 45 and 46 and is engageably secured to socket spring contact 41 against which center contact point 48 of the base of illuminating lamp 21 is urged.

From the foregoing description it will be seen that electrical current introduced through contact clip assembly 29 at the right side of the instrument as seen in Figure l passesthrough the corresponding contact clip 32 and the lamp supporting socket 24 to the threaded conductor base 49 and lamp 21 from whence the current is conducted through the iilament 5I of the right hand lamp, thence downwardly through center contact point 48, socket spring Contact 41, conductor rivet 43, and terminal lug 23, to the lamp 21 at the left lof the instrument as seen in Figure 1.

The current having been conducted from the right hand lamp 21 through terminal lug 23, it

can be seen that the current passes horizontally to the left through terminal lug 23, upwardly through lrivet 43', socket spring contact 41', center contact point 48 of left hand lamp 21 and -through the filament 5I to threaded conductor base 49 which is in threaded connection with lamp supporting socket 24. The return circuit to the electrica] source outside the instrument is completed through contact clip 32' at the left side of the instrument, thence through contact clip assembly 29" through lead wire 28' to the source of electrical energy.

When it is desired to replace a burned out lamp, it is only necessary that screw 2B be withdrawn and the lamp supporting assembly be removed from the casing I I whereupon a new lamp or lamps may be substituted for those which have :burned out. The lamp supporting assembly may then be replaced in the housing by inserting the lamps through apertures 25 and 25 in the bottom wall of the casing andvheld securely ,in place by screw 26.

By suitable modification it is possible to arrange the illuminating lamp ,circuit so that the lamps may be disposed inv parallel rather than in series as shown in the illustratedembodiment.

It is also contemplated that other minor modifications may be made in the arrangement of the elements illustrated and described herein without departing from the scope of the invention.

The invention is not limited to an assembly including two lamps as shown in the drawing inasmuch as a greater or smaller number of lamps may be employed if desired.

It is intended that the patent shall cover by sui-table expression in the appended claim whatever features of patentable novelty reside in the invention.

I claim:

Means for illuminating the interior of an instrument housing comprising, in combination: a housing having an outer wall of dielectric material provided with spaced openings, an assembly including, bolts mounted on an outer wall of said housing projecting into the interior thereof, sleeves carried by said bolts, and contact clips carried by said bolts positioned by said sleeves adjacent said spaced openings; and a detachable lamp assembly including a mounting strip of dielectric material detachably fastened to the eX- ternal face of said housing, a terminal lug inlaid in said dielectric strip, a pair of lamp sockets 5 6 mounted in spaced relation on said strip, the REFERENCES CITED shells of said lamp sockets being insulated from The following references are of record in the said lug and projecting through said openings to me of this patent: engage said contact clips, incandescent lamps in said sockets, the center contact points of said :3 UNITED STATES PATENTS lamps electrically connected to said lug by means Number Name Date of rivets engaged with said lug, and spring con- 1,118,969 Thompson Dec. 1, 1914 tacts in said sockets secured to said rivets, where- 1,756,070 Schupp Apr. 29, 1930 by upon connection of said bolts to a source of 1,963,234 Van Lyf July 31, 1934 electricity said incandescent lamps `are energized. 2,075,068 Stout Mar. 30, 1937 2,168,720 Trplett Aug. 8, 1939 WELDON C. EMERY. 2,195,975 Ribble et al. Apr. 2, 1940 2,210,698 Young Aug. 6, 1940 

